Full listing of The British Geological Survey Taxonomy database

Species name

Description

Dimensions

Carboniferous spores

Angulisporites splendidus Bhardwaj, 1954

Radial, trilete, camerate miospores. Amb rounded triangular to subcircular or oval. Miospores consist of inner body conformable in outline with equatorial margin, surrounded by exoexinal body with thickened equatorial rim approximately 5 µm wide. Trilete mark distinct, sutures straight, extending at least as far as the margin of the inner body; simple or accompanied by relatively low elevated, flexuous folds of the exoexine that extend decreasing in height to the equatorial margin of spore. Intexine relatively thick; forms inner body which occupies between two-thirds and three-quarters of the spore diameter. Exoexine thicker; extent of separation of exoexine from intexine difficult to ascertain but inner body commonly possesses independent compression folds suggesting separation in, at least, the equatorial region and part of the distal surface. Exoexine has thickened equatorial rim, similar to a cingulum, which occupies up to half the width of exoexinal extension. Exoexine infrapunctate.

Radial, trilete, acamerate, cingulate miospores. Amb triangular with concave or more rarely straight sides and rounded apices. Outline crenulate. Trilete mark distinct, sutures straight, simple or with low narrow thickened labra, extending to the inner margin of the cingulum. Intexine thin, forming wall of spore body. Exoexine closely adpressed over both proximal and distal surfaces but extended in the equatorial plane to form irregular narrow cingulum, 2–5 µm wide, with irregular crenulate margin but of more or less uniform thickness. Distal surface ornamented with thickened Y-shaped structure with the three components extending from the distal pole to the cingulum which they join in the radial positions. Margins of distal thickened ribs crenulate in the same style as the cingulum, individual ribs up to 10 µm wide. Proximal surface laevigate, distal surface including distal thickened ribs and the cingulum foveolate, with foveolae less than 2 µm in diameter. Foveolae may be randomly distributed or arranged in rows. Distal thickened ribs often bear two rows of foveolae running down their length.

Pollen grains with oval or fusiform outline. Specimens characterised by well-developed furrow which extends almost the complete length of the grain. Furrow sometimes contorted by folding, or accompanied on either side by thickened lip-like folds. Remainder of exine also folded with axes of irregular folds parallel to long axis of grain. Exine surface finely infrapunctate.

Radial, trilete, cingulizonate, camerate miospores. Amb rounded triangular to subcircular. Trilete mark distinct, sutures straight, extending to the equatorial margin of inner body, often obscured by elevated flexuous folds of the exoexine that extend decreasing in height to the equator of spore. Intexine thin, granulate, forming rounded triangular inner body. Exoexine relatively thick, extended in the equatorial plane to form differentially thickened zona consisting of two parts, an inner thickened part which appears to overlap the margin of the inner body on the distal surface and a wider thinner outer part which frequently appears faintly radially striated. Thinner outer section of zona may contain small radially orientated internal vacuoles. Distal exoexine bears prominent foveola in the polar region. Margin of foveola thickened to produce low thickened rim. A single foveola may be present with a circular or ‘clover leaf’ shape. Specimens with up to three separate distal foveolae also occur.

Radial trilete acamerate miospores. Amb circular–subcircular. Trilete mark distinct or obscured by ornamentation, sutures simple or accompanied by wide labra, extending more than three-quarters of spore radius. Ornament on entire distal surface and equatorial portion of proximal surface consists of rounded anastomosing ridges, some of which may be fused together to form an imperfect reticulum. Ridges variable in width along length and often have expanded tops particularly where ridges join. The channels and irregular lumina between the ridges are normally equal to or wider than the mean width of the ridges. Ridges 3–12 µm high and 5–15 µm wide. Exine up to 5 µm thick.

Radial, trilete miospores. Amb subcircular to rounded triangular. Trilete mark distinct, sutures straight, extending to or nearly to the spore margin; accompanied by elevated flexuous folds that extend, decreasing in height, to the inner margin of the equatorial crassitude with which they fuse laterally. Apical papillae common in the intertectal areas. Exine laevigate or infrapunctate, thickened in the equatorial region to form ill-defined crassitude with weak inner margin. Crassitude invaginated in the radial positions where it fuses with folds accompanying trilete sutures to form clearly defined curvaturae which run just on the proximal side of the equatorial margin. Distal surface of exine and equatorial margin ornamented with spinae and rare coni; elements 1.5–15 µm in height, and 1–5.5 µm in basal diameter. Approximately 20 elements project at the equatorial margin, elements normally discrete and more or less constant in size on individual specimens.

Radial, trilete, variably camerate miospores, intexine probably attached proximally and separated to variable degrees over the distal surface. Amb subcircular, oval or irregular due to folding. Trilete mark usually distinct, sutures straight or sinuous, simple or accompanied by narrow flexuous folds, extending almost to the equatorial margin where they fuse laterally with curvaturae that are coincident for most of their length with the equatorial margin. Exoexine densely sculptured with coni and pilate elements, 1–3.5 µm high and 0.5–2.5 µm in width, with grana up to 1 µm in height and width, interspersed between elements. Distribution of ornament variable, sometimes dense but elsewhere sparse with unornamented areas. Equatorial margin thickened to form ill-defined crassitude with poorly delimited inner margin. Secondary compression folds commonly arranged in a concentric style close to the equatorial margin.

Radial, trilete, acamerate miospores. Amb rounded triangular to subcircular. Trilete mark distinct or obscured by ornamentation, sutures simple, straight, extending between half and two-thirds of spore radius. Exine bears characteristic reticulate ornament, muri present on proximal surface, reduced in height and density but commonly developed parallel to sutures of trilete mark. Muri 8–20 µm high and approximately 3 µm wide at base, with distinctive papillate crests. Muri enclose a variable number of large lumina up to 30 µm in diameter, variable in shape. Crests of muri deeply incised to about half their height to form blunt, slightly pointed or clavate papillae.

Radial, trilete, acamerate miospores. Amb circular to rounded triangular. Trilete mark distinct or obscured by the ornamentation, sutures simple straight, extending between half and three-quarters of spore radius. Exine ornamented on entire distal surface and equatorial portion of proximal surface with muri which are up to 2 µm wide and 6–12 µm high. Muri enclose variable number of polygonal lumina which are of more or less uniform size on any individual but vary in size and number between individuals. Lumina vary in diameter up to 25 µm. Exine of lumina laevigate although infrequent small coni and spinae may occur.

Radial, trilete, camerate miospores. Amb of body and saccus circular to rounded triangular. Trilete mark distinct, sutures straight, extending to or almost to margin of inner body, accompanied by elevated flexuous folds of the exoexine which extend, decreasing in height, almost to the equatorial margin of the exoexinal body. Ends of elevated exoexinal folds connected laterally with narrow, fine, curvatural ridges that in proximo-distal compression are located, for much of their length coincident with the equatorial margin of the saccus, the exception being in the radial positions where minor invagination takes place. Intexine thinner than exoexine, forms inner body that may possess peripheral taper-point compression folds, indicating significant separation of the two exine layers. Exoexine thin, granulate with fine narrow limbus, forms saccus and is commonly extensively folded.

Radial, trilete, camerate miospores. Amb circular, subcircular or rounded triangular, outline of inner body more or less conformable and occupying two-thirds to four fifths of the spore diameter. Trilete mark distinct or obscured by folding, sutures straight, extending at least three-quarters of the inner body radius, commonly accompanied by elevated flexuous folds of the exoexine that extend decreasing in height to the equatorial margin of spore. Intexine thin, laevigate, forms well-defined inner body with independent compression folds indicating major separation of the two exine layers. Exoexinal body wall 1–2.5 µm thick; exoexine infrapunctate, ornamented over entire distal surface and equatorial portion of proximal surface with sharply pointed coni and spinae, many of which may have bulbous bases. Elements with bulbous bases more commonly located in the polar regions with simple, sharply-pointed coni and spinae at the equator. Elements 2–8 µm high (commonly 2–5 µm) and 2–4 µm in basal diameter. Exoexine commonly folded due to compression.

Radial, trilete, camerate miospores. Amb circular to rounded-triangular with undulating equatorial margin. Trilete mark distinct, sutures straight, simple or with low, narrow, thickened labra; extending between two-thirds and the full spore radius. Intexine thin, forms irregular, extensively folded, inner body which is separated from the exoexine over a significant part of its surface. The two layers appear to be in contact at least at the contact areas. Exoexine 1–4 µm in thickness, ornamented with variably shaped verrucae which show basal coalescence to form short, irregular ridges. Elements densely distributed and separated by narrow channels of unornamented exoexine. Up to 30 elements project at the equator to produce undulating margin. Verrucae up to 3 µm high at equator. Ornament reduced or absent on the proximal surface.

Radial, trilete, cingulate miospores. Amb circular to subcircular, consisting of circular to subcircular spore body surrounded by more or less conformable cingulum. Trilete mark distinct, sutures simple, or accompanied by low, thickened labra up to 8 µm wide, which extend to the margin of the spore body. Sutures straight, extending between three-quarters to almost the full radius of the spore body. Exoexine extended in the equatorial plane to form undifferentiated cingulum, 6–16 µm in width. Distal surface bears conspicuous, widely spaced, relatively low, broad, smooth, rounded muri that are connected in several places to each other and to the cingulum. Muri slightly sinuous, irregular in pattern, 8–17 µm wide and 4–7 µm high. Remainder of exine laevigate.

Radial, trilete, cingulate miospores. Amb circular, subcircular to rounded triangular. Trilete mark distinct, sutures straight, extending to margin of spore body, simple or accompanied by low narrow thickened labra which typically become expanded equatorially to form triangular thickened areas that fuse to the proximal surface of the cingulum. Exine laevigate. Intexine forming spore body rarely discernible. Exoexine closely adpressed to intexine but extended in the equatorial plane to form thickened, undifferentiated cingulum, 5–15 µm wide. Exoexine developed into second ring of thickening mid way between the equator and the distal pole with irregular, radially-orientated thickened ribs in the inter-radial positions sometimes connecting it to the cingulum. A distal polar thickening 5–10 µm in diameter is also developed on the exoexine.

Radial, trilete, cingulate miospores. Amb subcircular to rounded triangular. Trilete mark distinct, sutures straight, sometimes open, extending to the inner margin of the cingulum, accompanied by broad prominent labra up to 20 µm in overall width. Intexine relatively thin; forms rounded triangular to subcircular inner body. Exoexine extended in equatorial plane to form undifferentiated cingulum, up to 14 µm wide. Proximal surface laevigate. Distal surface ornamented with three muri arranged in a triangular pattern with the apices of the triangle joining the cingulum in the inter-radial positions. Muri vary between 8–12 µm in width and are often slightly expanded where they fuse with the cingulum. Remainder of exine laevigate to scabrate.

Radial, trilete, camerate, zonate miospores. Amb rounded triangular to subcircular. In lateral compression proximal surface low, pyramidal; distal surface hemispherical. Trilete mark distinct, sutures straight, extending to margin of inner body, accompanied and obscured by elevated, flexuous folds of the exoexine, up to 8 µm high in the polar region but decreasing in height to the equatorial margin. Intexine thin, forming rounded triangular to subcircular inner body. Exoexine extended in the equatorial plane to produce strongly bizonate zona up to 25 µm wide. Exoexine thicker over distal surface of inner body and extending into the inner part of the zona, outer part of zona thinner and weakly striated. Two exine layers normally closely adpressed but minor separation may occur in the equatorial plane and over the more equatorial portions of the distal surface. Exoexine surface finely infrapunctate, distal surface bears distinctive ornament of large pointed coni and spinae with expanded bases; height of elements 4–14 µm, basal diameter 2–7 µm. Elements variable in distribution with maximum concentration usually occurring on the inner thicker zone of the zona close to the margin of the spore body.

Radial, trilete, camerate miospores. Amb subcircular to rounded triangular with convex sides and rounded or slightly pointed apices. Trilete mark distinct or obscure; sutures straight or sinuous, extending to margin of spore body, accompanied by elevated flexuous folds of the exoexine which extend, decreasing in height, to the equatorial margin of the spore. Intexine thin, forming subcircular to rounded triangular inner body. Exoexine slightly thicker over distal surface and extended in the equatorial plane to form slightly fibrous zona 8–18 µm in width. Distal and more equatorial portions of proximal surface of exoexine ornamented with sparse to closely spaced spini, coni and grana. Elements either discrete or fused at their bases to form short irregular cristae or rugulae. Spinae 1–5 µm high and 0.5–2 µm in basal diameter, coni 1–3 µm in height and grana up to 1 µm high. Exoexine of proximal surface thin and crumpled and in many cases folded along the line of the margin of the intexine.

Radial, trilete, cingulizonate, camerate miospores. Amb rounded triangular to subcircular, in lateral profile proximal surface flattened, low or pyramidal; distal surface hemispherical. Trilete mark distinct, sutures straight, extending to, or almost to, the equatorial margin of spore body, accompanied by elevated flexuous folds of the exoexine which extend decreasing in height to the margin. Exine composed of two layers. Intexine, thin, forms rounded triangular to subcircular inner body. Exoexine normally closely adpressed to the intexine but displays limited separation in the equatorial region. Exoexine extends to form bizonate cingulum. Maximum thickness of the exoexine developed over the distal surface and in the region of the cingulum adjacent to inner body margin. Outer zone of cingulum thinner and wider; sometimes appears weakly striated. Distal surface of exoexine ornamented with sharply pointed coni and spinae. Elements 2–10 µm high (commonly 3–5 µm) with the longest most slender elements located close to the junction of the body and cingulum.

Radial, trilete, cingulate miospores. Amb circular to subcircular. Trilete mark distinct, sutures straight, extending almost to spore body margin, accompanied by broad, flat labra, extending 6–10 µm on either side of the sutures and having undulate outer margins. Intexine laevigate to infrapunctate, forms circular to subcircular inner body. Exoexine extended in the equatorial plane to form smooth dense cingulum surrounded by more transparent, less robust, equatorial border which has a frilled membranous appearance. Boundary between the two parts of the cingulum is smooth. In some specimens outer membranous part of the cingulum appears to overlap thicker inner part particularly on the distal surface. Thinner outer membranous section may be variable in width creating undulate equatorial margin.

Radial, trilete, cingulate miospores. Amb rounded triangular to subcircular, inner body conformable in outline with the equatorial margin. Trilete mark distinct to indistinct, sutures simple, straight, extending to margin of the inner body, sometimes accompanied by low narrow labra. Intexine thin, laevigate, forms inner body conformable in outline with the equatorial margin. Exoexine closely adpressed to intexine over both proximal and distal surfaces but extended in the equatorial plane to form more or less undifferentiated uniform cingulum which occupies 20–35 % of the spore radius. Distal surface of exoexine ornamented in the region underlying the inner body with prominent rounded tubercles and verrucae, elements normally discrete but variable in size, height up to 6 µm and basal diameter varying between 3–15 µm. Elements commonly distributed in a concentric manner in the region adjacent to the body-cingulum boundary with a single, frequently larger, element developed in the distal polar region. Ornamentation absent from the majority of cingulum, margin smooth or minutely indented. Surface of exoexine between verrucose elements smooth or minutely granulate.

Radial, trilete, cingulizonate miospores. Amb rounded triangular to subcircular. Trilete mark indistinct, sutures when seen, simple, straight or flexuous, extending to, or almost to, inner body margin. Intexine thin, laevigate, forming poorly defined inner body that may show evidence of minor separation from the exoexine in the equatorial plane. Exoexine extended in the equatorial plane to form weakly bizonate cingulum consisting of a narrow darker inner zone which appears to overlap the equatorial margin of the inner body, particularly over the distal surface, and a wider thinner outer zone. Outer zone of cingulum bears a variable number of radially orientated elongate vacuoles that appear to be independently developed at two levels, presumably underlying both proximal and distal surfaces. Exoexine surface also bears numerous radially orientated striations and plications, which extend to the equatorial margin. Vacuoles separated by narrow walls. Distal polar exoexine may bear scattered grana or small verrucae.

Radial, trilete, miospores. Amb including corona rounded triangular to circular. Outline of spore body triangular with rounded apices and concave sides. Trilete mark distinct, sutures simple or with weak narrow low labra; straight, extending almost to equatorial margin. Well-developed corona composed of setae up to 1 µm wide and more or less in full lateral contact throughout their length. Corona attached to exine just proximally of the equatorial margin. Maximum width of corona, including overlap on proximal side, 17–28 µm; occurs in the inter-radial position. In the radial positions the corona may be as narrow as 2 µm and may be attached nearer to the proximal pole so that on compression it may appear to cross the angles of the spore body. Exine moderately thick, laevigate to scabrate, folding rare.

Radial, trilete, cingulate miospores. Amb broadly rounded triangular to subcircular, margin usually smooth, but occasionally undulate to uneven or highly involute. Trilete mark distinct, sutures straight, simple or with low narrow labra, extending to inner margin of the cingulum. Intexine relatively thin forming subcircular to rounded triangular inner body. Exoexine extended equatorially to form differentially thickened cingulum consisting of three zones, each varying from 5 to 17 µm in width. The inner thickened zone is broader and more prominent than the outer marginal thickened zone, which is commonly reduced or discontinuous. The thinner median zone may be reduced to a mere line but in other specimens may be of significant width. Radially orientated thickenings may be present on the distal surface and take the form of a Y-shaped structure attached to the cingulum in the inter-radial positions. Faint proximal thickenings may arise from the radial positions but they scarcely extend poleward beyond the inner thickened zone of the cingulum.

Radial, trilete, camerate miospores. Amb convexly rounded triangular to subcircular. Trilete mark distinct; sutures straight or slightly curved, extending to margin of the inner body, accompanied by elevated flexuous folds of the exoexine which extend decreasing in height to almost the equatorial margin of the spore. Ends of exoexinal folds fuse laterally with curvaturae imperfectae, which are slightly invaginated in the radial position but are coincident with the equatorial margin for much of their length. Intexine thin; forms subcircular to rounded triangular inner body which occupies half to three-quarters of the spore diameter. Sometimes eccentrically placed, suggesting proximal attachment only. Exoexine ornamented with distal reticulum consisting of subcircular, polygonal or irregularly shaped lumina separated by narrow muri. Muri 0.5–2 µm wide; bear an ornament of small coni and spinae up to 2 µm high. Muri commonly exhibit progressive breakdown to form short rugulae or eventually residual coni and verrucae. Lumina up to 4 µm in diameter, variable in shape and size even on same specimen. Narrow limbus may be present at the equatorial margin, which may in part coincide with curvaturae imperfectae. Apical papillae sometimes present. Compressional folds common.

Radial, trilete, acamerate miospores. Amb subtriangular, with broadly rounded apices, to subcircular, outline of body more triangular. Trilete mark distinct; sutures straight, simple or with low narrow labra, extending between three-quarters and almost the full radius of the body. Exine laevigate. Zona widest (up to 6 µm) in the inter-radial position but significantly reduced at the apices. Zona normally bizonate with inner thicker zone of more or less uniform width, apparently overlapping margin of inner body at least on the distal surface. Outer thinner zone variable in width.

Radial, trilete, camerate miospores with a bilaterally symmetrical appearance due to the presence of an elliptical saccus-like exoexinal structure. Amb oval but occasionally sub-circular. Trilete mark distinct to indistinct; sutures straight, extending up to two-thirds of spore body radius, sutures often of unequal length on individual specimens. Intexine forms circular to oval inner body; long axis of inner body rarely orientated obliquely to the long axis of the miospore. Exoexine infrapunctate with a narrow dark zone often occurring where the saccus overlies the equatorial margin of the spore body. Radial compression folds infrequently developed.

Radial, trilete, camerate miospores with a bilateral appearance due to the presence of an elliptical saccus-like exoexinal structure. Amb oval to subcircular, body oval to subcircular. Trilete mark distinct to indistinct; sutures simple, straight, extending between two-thirds and almost the full body radius. Exoexine infrapunctate with a narrow dark zone often occurring where the saccus overlies the equatorial margin of the spore body. Longest axis of the inner body usually oblique to the long axis of the miospore, rarely at right angles to it. Folding infrequent.

Radial, trilete, camerate miospores with a bilaterally symmetrical appearance due to presence elliptical saccus-like exoexinal structure. Amb oval to ovoid. Inner body circular to oval with long axis parallel to the long axis of the miospore overall. Trilete mark not always visible; sutures simple, straight extend to, or almost to, inner body margin. Two of the sutures are commonly orientated parallel or nearly parallel to the long axis of the miospore with the third suture at right angles to them. Intexine of inner body relatively thin, laevigate or finely infrapunctate; long axis of inner body approximately three-quarters of miospore long axis, short axis of inner body almost equal in width to the short axis of the miospore. Exoexine thicker than intexine, laevigate to finely infrapunctate.

Radial, trilete, camerate miospores. Amb rounded triangular to subcircular. Trilete mark distinct to obscure; sutures, when seen, extend to margin of ill-defined inner body, straight and accompanied by narrow sinuous exoexinal folds which extend to or almost to equatorial margin. Ends of exoexinal folds fuse laterally with curvaturae which are more or less coincident with equatorial margin except in radial positions where minor invagination occurs. Intexine often barely perceptible; forms ill-defined inner body, which occupies approximately half miospore diameter with outline conformable with equatorial margin. Exoexine thicker than intexine. Proximal surface laevigate except at the radial margins. Distal surface densely and uniformly ornamented with small, wide-based spinae up to 3 µm in height together with infrequent coni and grana. Elements may be discrete or may be basally fused to form low rugulae or cristae. Equatorial margin of exoexine thickened due to presence of curvatural ridges.

Radial, trilete, camerate miospores. Amb convexly rounded triangular to almost circular. Trilete mark distinct; sutures straight, commonly accompanied by elevated folds which extend, decreasing in height, almost to the equatorial margin of the spore where they fuse with curvaturae perfectae which are invaginated in radial positions. Exine slightly thickened at the equatorial margin to form limbus. Exoexine scabrate to punctate; irregularly ornamented on the distal surface, at the equatorial margin and around the curvaturae with mixed rounded elements which are typically grana but may include sparse verrucae. Apiculate and biform elements are rare. Ornament reduced or absent in the contact areas. Intexine of inner body thin, laevigate; inner body rarely distinct, occupies one-third to one half of the spore diameter, attached to exoexine on proximal surface only.

Radial, trilete, camerate miospores. Amb rounded triangular to subcircular. Trilete mark distinct, sutures obscured by elevated sinuous folds of the exoexine which extend, decreasing in height, to the equatorial margin. Well-defined inner body formed by thin intexine; outline circular to subcircular. Equatorial margin of exoexine together with that part of the proximal surface which is invaginated opposite the ends of the trilete sutures, thickened to form equatorial border. Equatorial border and distal surface ornamented with fine vermiculate or reticulate ridges. Ridges surmounted by small spinae. Exoexine of contact areas laevigate.

Radial, trilete, camerate miospores. Amb convexly rounded triangular. Trilete mark distinct, sutures straight though often obscured; extend to margin of inner body, accompanied by elevated flexuous folds of exoexine which extend decreasing in height, to the equatorial margin. Intexine thin, forms inner body, which is conformable in outline with the amb of the spore and occupies approximately three-quarters of the total spore diameter. Exoexine 3–6 µm thick, extended in the equatorial plane to form solid flange. Exoexine prominently ornamented with large spini which are concentrated in the equatorial region, commonly reduced in the distal polar region and completely absent from contact areas of proximal surface. Spini have broad, often bulbous bases and sharply pointed terminations; height 4–19 µm and basal diameter 2–6 µm. Spina size variable between specimens but uniform on any one specimen.

Monolete miospores. Amb ovoid, subtriangular or irregular. Miospore consists of ovoid to subcircular spore body with a pronounced patinate crassitude either over the distal surface or the distal and lateral surfaces. Monolete mark usually distinct, suture straight or curved; simple; length approximately three-quarters or more of the spore body radius. Suture commonly parallel to the long axis of the spore. Intexine of spore body relatively thin, laevigate. Exoexine thickened over part of the distal surface or at least in part in the equatorial plane to form patinate crassitude which may in some cases overlap a significant part of the spore body on the proximal surface. Profile of crassitude in compressed specimens crescentic or sub-rectangular, surface smooth or finely roughened. Boundary between crassitude and spore body gradational or abrupt.

Radial, trilete, acamerate miospores. Amb irregularly triangular with more or less straight sides and rounded, flat or lobate apices. Shape dependent on the extent of exine ornamentation. Proximal surface flattened, distal surface inflated hemispherical. Trilete mark distinct to indistinct, sutures simple, straight; extending from two-thirds to the full spore radius. Proximal exine laevigate but distal exine ornamented with irregular pattern of ridges and verrucae. Verrucae variable in size and distribution; frequent fusion occurs between the bases of adjacent elements to produce an ill-defined reticulate pattern. Thickening of the exine at radial apices occurs to produce a variable crassitude. When associated with verrucae, this projects at the equatorial margin. Crassitudes, may in some cases, extend into inter-radial areas. Crassitudes vary from 2–7 µm across when measured along a given radius, and are 10–17 µm in width. Exine moderately thick.

Radial, trilete, acamerate miospores. Amb triangular to sub-triangular with rounded apices and straight to concave sides. Trilete mark distinct; sutures simple, straight, extend from two-thirds to the full radius of the spore body. Spore body more or less laevigate. Exoexine extended in the equatorial plane to produce variable cingulum which is narrow (2–4 µm) in the inter-radial areas but greatly expanded in the radial positions to form prominent auriculae. Outer margins of auriculae thickened and laterally expanded to create large, homogenous cushion-like caps with a smooth to crenulate surface. Caps approximately 7 µm across when measured along a radius, and are 30 µm wide.

Radial, trilete, acamerate miospores. Amb circular, subcircular or oval. Trilete mark often distinct; sutures when seen, simple, straight, extending between one-third and one-half the spore radius. Exine, 1–3 µm thick, ornamented on distal surface and equatorial portion of proximal surface with cylindrical shaft-like elements which are 2–10 µm high and 1–3 µm wide, with a prominent constriction near the top and a second near the base. Terminus of each shaft-like element normally flat but commonly surmounted by a single spina or conus up to 4.5 µm high. Rare small coni and spini may be interspersed between the longer biform elements. Ornamentation elements variable in size between specimens but commonly uniform on any single specimen. Contact areas laevigate.

Radial, trilete, acamerate miospores. Amb circular to subcircular. Trilete mark frequently indistinct or torn; sutures when seen are short, simple and straight, extending up to one-sixth of spore radius. Exine 1–2 µm thick, ornamented on distal surface and equatorial portion of the proximal surface with variable squat biform baculate or pilate projections arranged randomly over the surface. Elements variable in shape and size on any one specimen; individual elements up to 4.5 µm high and 1.0–1.5 µm in basal diameter, widening towards the apex. At the terminus of each element are one to three rounded heads, each surmounted by a single thin tapering spina. Between the larger biform elements, slender tapering spinae 2–4 µm long and up to 1 µm wide may occur.

Radial, trilete, cingulizonate miospores. Amb rounded triangular with convex sides and rounded apices, sometimes subcircular. Trilete mark distinct; sutures straight, extending to the margin of the inner body, accompanied by elevated flexuous folds of the exoexine which extend, decreasing in height, to the equatorial margin. Intexine thin, forming rounded triangular inner body, frequently folded independently and withdrawn from the exoexine at least in the equatorial plane. Exoexine thin over proximal surface but thicker over distal surface and extended in the equatorial plane to form variably thickened cingulizona consisting of two zones. Inner thinner zone contains numerous internal radially orientated vacuoles separated by thin walls. Outer zone thicker and separated from the inner thinner zone by an irregular boundary coinciding with the limits of vacuolation. Distal surface of exoexine ornamented with pointed or rounded coni up to 3 µm high and 3.5 µm in basal diameter, interspersed with galeae consisting of a bulbous base surmounted by a small sharply pointed conus. Ornamentation reduced over the outer part of the cingulum to small coni. Well-developed cuniculus developed in the equatorial plane adjacent to the margin of the intexine.

Radial, trilete, cinguli-camerate miospores. Amb rounded triangular to subcircular. Outline of inner body may be conformable with equatorial margin of spore or more circular resulting in the equatorial cinguli-zonate structure being wider in the radial positions. Trilete mark distinct, sutures straight, extending to margin of inner body, accompanied by elevated, flexuous folds of the exoexine, up to 4 µm in the polar region but decreasing in height and extending to the equatorial margin. Intexine thin, laevigate or finely infrapunctate, forming inner body. Exoexine closely adpressed to intexine except in the equatorial plane where a well developed cuniculus indicates limited separation. Exoexine extended in the equatorial plane to form bizonate cingulum consisting of a thinner, inner, extensively vacuolated zone with closely spaced radially orientated vacuoles separated by narrow walls, and a thicker, outer zone. Distal surface of exoexine bears galeate ornament of variable density; elements are largest and most densely distributed in the distal polar region and finer and less densely distributed towards the equatorial margin. Small, sharply pointed coni may be located in the spaces between the galeate elements. Individual galeae up to 10 µm high and 7 µm in basal diameter, consisting of a rounded basal boss surmounted by a sharply pointed, slender spina. Fusion between bases of adjacent elements forms irregular vermiculate elements with common spinose crests, particularly in the polar region. Numerous elements project at the equatorial margin.

Radial, trilete, camerate, cingulizonate miospores. Amb convexly rounded triangular. Trilete mark distinct to indistinct, sutures straight, extending to margin of inner body, accompanied by low, slightly elevated exoexinal folds which decrease in height towards the ends of the sutures. Height of folds in polar region approximately 2.5 µm. Exine two layered. Intexine thin, forms inner body conformable in outline with equatorial margin, surface laevigate. Exoexine closely adpressed to intexine over proximal and distal surface but separated at least to some extent in the equatorial plane where a well-developed narrow cuniculus is developed. Exoexine thin over proximal surface but slightly thicker distally and extended in the equatorial plane to form differentially thickened tapering cingulum. Cingulum consists of inner thicker zone that appears in part to overlap the equatorial margin of the inner body, up to 8 µm wide. In many specimens large numbers of small elongate internal vacuoles, separated by narrow walls, appear to be located within this portion of the cingulum. Individual vacuoles up to 5 µm in length. Outer part of cingulum thin and sometimes weakly radially striated. Distal exoexine bears a dense ornament of coni, grana and small spini, elements up to 3 µm in height and 2 µm in basal diameter. Elements normally discrete but some basal coalescence occurs. Ornament more sparsely distributed on the cingulum and at the equatorial margin is limited to small conate projections.

Radial, trilete, camerate, cingulizonate miospores. Amb convexly rounded triangular. Trilete mark distinct or indistinct if obscured by ornament; sutures straight, extending to margin of inner body, simple or accompanied by elevated flexuous folds of the exoexine, up to 4 µm high in polar region, which extend, decreasing in height, to the margin of the body or onto the cingulum. Exine two layered. Intexine thin, laevigate, forms inner body conformable with the equatorial outline. Exoexine closely adpressed to intexine in proximal and distal positions but separated from intexine in the equatorial plane where a well-developed cuniculus is located. Exoexine extended in the equatorial plane to form poorly differentiated bizonate cingulum. Inner thicker zone of cingulum overlaps the equatorial margin of inner body and may contain numerous internal radially orientated vacuoles. Outer zone of cingulum thinner and narrower. In some specimens differentiation of the cingulum is difficult to discern. Distal surface of exoexine densely ornamented with discrete or confluent verrucae up to 6 µm in diameter. Elements may fuse to form short irregular ridges. Verrucae are most densely distributed in the distal polar region where the largest elements are also located. Towards the equatorial margin, elements become progressively smaller and more sparsely distributed. Equatorial margin uneven but rarely displays coarse projecting ornamentation. Verrucae surmounted by small mammoid coni may be present in the distal polar region.

Discontinuous terminal rim present; inner body not apparent. Left side shows incipient weakness of the outer wall shown by separation of the rim from the rest of the wall. Cell material distinct, granular in appearance.

Detail of specimen shown in image Flowerpt 66398_Y41_1. Chain of ovoid cells. The cells to the right both possibly contain slightly shrunken inner bodies. In the middle cell the inner body is attached to the inner surface of the terminal rims on both sides of the cell. Terminal rims are not well displayed between the two right hand cells. Both the inner body wall and the outer cell wall appear to be smooth and less than 1µm thick.

Chain with relatively well preserved cells close in form to some of the Alpine specimens. The right edge of the right hand cell appears not to have been connected to another cell. The left cell has clearly been detached from another cell.

Chain with relatively well preserved cells close in form to some of the specimens from the Mazzin Member, Austria. The right edge of the right hand cell appears not to have been connected to another cell. The left cell has clearly been detached from another cell.

Chain of 5 cells. Several of the cells have partially collapsed walls between the terminal rims, suggesting that the latter are the most rigid part of the cell structure. The second cell from the right is a 3 way cell.

End on view orientated normal to the terminal plane. Rim appears rectilinear in form, thickening may be incipient or as a result of folding. No pore or aperture visible in the terminal face. Terminal face planar.

Elongate cell with well developed diagonal fold. The right terminal rim is partially detached along the incipient weakness in the cell wall at the base of the terminal rim. The left terminal rim is very well developed.

Cell with well developed longitudinal fold. This and other specimens indicate a cell wall corrosion form that is similar in appearance to ‘exfoliation’. That the wall appears to ‘flake off’ in this way suggests that it may be lamellate in structure.

Detail of specimen showing a complete cell joined to a partial cell that has broken at the weakness at the base of the terminal rim. Illustrates the fine suture at the join between the adjacent terminal rims.

This specimen illustrates the characteristic ‘Christmas cracker’ morphology of cell chains after vigorous ultrasound treatment. The central cell shown is intact but the two adjacent cells are broken at the base of their respective terminal rims. This illustrates the comparative strength of the bonds between terminal rims.

This specimen illustrates the characteristic ‘Christmas cracker’ morphology of cell chains after vigorous ultrasound treatment. The central cell shown is intact but the two adjacent cells are broken at the base of their respective terminal rims. This illustrates the comparative strength of the bonds between terminal rims.

Oblique image of specimen shown in image ‘6403434_2_T1_Stub1_15.tif’ (Austria T1 6403434 2 Stub 1). Shows 3D shape of the compressed cell. The extent and pattern of folding indicates that the cell was originally ovoid in shape.

Oblique image of specimen shown in image ‘6403434_2_T1_Stub1_15.tif’ (Austria T1 6403434 2 Stub 1). Detail illustrates the thickness (approx. 0.75µm), and apparently homogeneous nature of the cell wall. Area within presumably represents the internal cavity of the cell. The inner surface of the wall illustrated appears to be striated.

Shows some of the range of cell size, shape and wall thickness within a single field of view. To the right are cells similar to those of the Greenland and Moura material. To the left are short ovoid cells.

The two prominent dark cells pictured here have inner bodies which almost fill the cell cavity. The differing transparency of the cells illustrated may be due to natural variation in the thickness of one or both of the cell walls.

The middle cell displays a slightly shrunken inner body where the inner wall is no longer adpressed to the inner surface of the outer cell wall but has retreated a few microns. Note that the inner cell wall is still adpressed to the outer cell wall at the termini. The lack of a strong transparency difference between parts of the cell showing the inner and outer walls indicates that the inner body has a thin wall.

The cell displays a slightly shrunken inner body where the inner wall is no longer adpressed to the inner surface of the outer cell wall but has retreated a few microns. Note that the inner cell wall is still adpressed to the outer cell wall at the termini.

Main cell pictured shows how shrinkage of the inner body occurs mainly in the middle parts of the cell. The inner body rarely detaches from the inner surfaces of the terminal rims unless shrinkage is very advanced.

Detail of specimen shown in image 6403380_NLD36_P5_1. Chain of three cells. Right side of chain. Illustrates attachment of the inner body to the termini of the outer wall. A helical twist may be present in the inner body of the right cell. Possibly such a twist is responsible for common diagonal folds.

Elongate cell bent in the centre. Right hand part of the cell shows ‘striations’ in the outer cell wall orientated parallel to the long axis of the cell. These striations may be the result of shrinkage of the outer cell wall.

Dark coloured (thick walled) specimen; displays very distinct inner and outer cell walls. Outer cell wall 1-1.5µm thick; outer surface very finely granulate (grana only just resolvable under oil x100). Faint shrinkage folds in the outer cell wall are present close to the termini. In these areas the terminal rims are ‘pinched’ i.e. much narrower than usual perhaps called by shrinkage. Inner cell wall 1 µm thick or less; appears smooth. Detached from the inner surface of the outer cell wall only close to the termini. Width of cavity between the two cell walls max. 3µm. Termini of the inner body still attached to the inner surface of the terminal rims. Small cavity at the terminus of the inner body visible on the right side of the cell. Cell material amorphous.

Detail of specimen shown in image 5031_Conisboro_F24_4_2. Cell with very constricted terminal rim. This specimen suggests that there are three wall layers in the cell which are only evident at the termini, and which, over the rest of the cell, are tightly adpressed. At the terminal rim a slight separation is evident.

Cell relatively light in colour due to the comprehensive collapse of the inner body. The very dark amorphous to granulate cell material is seen to be enveloped in the very thin, delicate inner body which is twisted and attached to the cell wall at the right terminal rim.

Cell relatively light in colour due to the comprehensive collapse of the inner body. The very dark amorphous to granulate cell material is seen to be enveloped in the very thin, delicate inner body which is twisted and attached to the cell wall at both ends. At the right is a strand of material which may represent the shrunken inner body of a previously adjacent cell.

Cell with irregular outline and a thin outer cell wall (0.5µm or less); contains a distinct, highly folded inner body. The inner body is in a partly shrunken state but is clearly attached to the inner surface of the terminal rims at both ends of the cell.

Approximately half of a large, well developed cell with a distinct terminal rim. A very shrunken and twisted inner body envelopes a mass of dense granulate cell material. The enveloping inner body forms a spindle shape. Terminus of inner body still attached to the inner surface of the terminal rim.